US4848718A - Apparatus for molding heat weldable pipe fittings - Google Patents

Apparatus for molding heat weldable pipe fittings Download PDF

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Publication number
US4848718A
US4848718A US07/040,840 US4084087A US4848718A US 4848718 A US4848718 A US 4848718A US 4084087 A US4084087 A US 4084087A US 4848718 A US4848718 A US 4848718A
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US
United States
Prior art keywords
core
apparatus according
molding
parts
apparatus
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Fee Related
Application number
US07/040,840
Inventor
Gordon Harrison
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
DuPont UK Ltd
Uponor Innovation AB
Original Assignee
EI Du Pont de Nemours and Co
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority to GB8609933 priority Critical
Priority to GB08609933A priority patent/GB2189737A/en
Application filed by EI Du Pont de Nemours and Co filed Critical EI Du Pont de Nemours and Co
Assigned to DU PONT (U.K.) LIMITED, WEDGWOOD WAY, GB-STEVENAGE, A CORP. OF UNITED KINGDOM reassignment DU PONT (U.K.) LIMITED, WEDGWOOD WAY, GB-STEVENAGE, A CORP. OF UNITED KINGDOM ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: HARRISON, GORDON
Publication of US4848718A publication Critical patent/US4848718A/en
Application granted granted Critical
Assigned to UPONOR B.V. A CORPORATION OF THE NETHERLANDS reassignment UPONOR B.V. A CORPORATION OF THE NETHERLANDS ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: E.I DU PONT DE NEMOURS AND COMPANY, A CORP. OF DE
Assigned to UPONOR INNOVATION AB reassignment UPONOR INNOVATION AB ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: UPONOR BV
Anticipated expiration legal-status Critical
Expired - Fee Related legal-status Critical Current

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    • BPERFORMING OPERATIONS; TRANSPORTING
    • B29WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29DPRODUCING PARTICULAR ARTICLES FROM PLASTICS OR FROM SUBSTANCES IN A PLASTIC STATE
    • B29D23/00Producing tubular articles
    • B29D23/001Pipes; Pipe joints
    • B29D23/003Pipe joints, e.g. straight joints
    • B29D23/005Pipe joints, e.g. straight joints provided with electrical wiring
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B29WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29CSHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C33/00Moulds or cores; Details thereof or accessories therefor
    • B29C33/12Moulds or cores; Details thereof or accessories therefor with incorporated means for positioning inserts, e.g. labels
    • B29C33/123Moulds or cores; Details thereof or accessories therefor with incorporated means for positioning inserts, e.g. labels for centering the inserts
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B29WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29CSHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C45/00Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor
    • B29C45/14Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor incorporating preformed parts or layers, e.g. injection moulding around inserts or for coating articles
    • B29C45/14065Positioning or centering articles in the mould
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B29WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29CSHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C45/00Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor
    • B29C45/17Component parts, details or accessories; Auxiliary operations
    • B29C45/26Moulds
    • B29C45/261Moulds having tubular mould cavities
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B29WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29CSHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C70/00Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts
    • B29C70/68Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts by incorporating or moulding on preformed parts, e.g. inserts or layers, e.g. foam blocks
    • B29C70/70Completely encapsulating inserts
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10TTECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T29/00Metal working
    • Y10T29/49Method of mechanical manufacture
    • Y10T29/49002Electrical device making
    • Y10T29/49082Resistor making
    • Y10T29/49083Heater type
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10TTECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T29/00Metal working
    • Y10T29/49Method of mechanical manufacture
    • Y10T29/49002Electrical device making
    • Y10T29/49082Resistor making
    • Y10T29/49087Resistor making with envelope or housing
    • Y10T29/49096Resistor making with envelope or housing with winding
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10TTECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T29/00Metal working
    • Y10T29/49Method of mechanical manufacture
    • Y10T29/49002Electrical device making
    • Y10T29/49082Resistor making
    • Y10T29/49101Applying terminal
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10TTECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T29/00Metal working
    • Y10T29/49Method of mechanical manufacture
    • Y10T29/49002Electrical device making
    • Y10T29/49117Conductor or circuit manufacturing
    • Y10T29/49174Assembling terminal to elongated conductor
    • Y10T29/49176Assembling terminal to elongated conductor with molding of electrically insulating material

Abstract

Apparatus and method for producing heat weldable, thermoplastic, tubular pipe fittings for use with heat weldable piping or tubing using a core in a molding machine having at least one pivoted segment collapsible inwardly of the core, each segment bearing radial projections to facilitate winding a heater wire and/or to receive a terminal post during the molding operation.

Description

BACKGROUND OF THE INVENTION

This invention relates to apparatus and to a method for producing heat weldable, thermoplastic, tubular pipe fittings for use with heat weldable piping or tubing.

Heat weldable thermoplastic tubular fittings are known in which there is, on the inner surface of the fitting, or embedded in the fitting, a coil of wire which enables the fitting to be heated electrically so as to melt the plastic and fuse the fitting to thermoplastic pipes or tubes.

An object of the invention is to provide an improved method and apparatus for producing such pipe fittings.

SUMMARY OF THE INVENTION

In accordance with the present invention there is provided an apparatus for molding heat weldable thermoplastic tubular fittings, the apparatus comprising a core having at least one pivoted segment collapsible inwardly of the core, each segment bearing radial projections adapted to facilitate winding heater wire and to hold the heater wire in position during subsequent moulding. The radial projections may also receive and support terminal posts during a molding operation.

The present invention further provides a method of producing a thermoplastic welding pipe fitting comprising:

winding a heater wire on the outer surface of a molding core, the molding core having at least one inwardly retractable segments carrying radially projecting posts;

placing a metallic electrically conductive terminal over each post to provide for attachment of the wire;

molding the fitting by placing the core in a molding machine and injecting thermoplastic material so as to mold the fitting and terminal post surrounds in situ;

inwardly retracting each retractable segment to remove the radially projecting posts from the terminals; and

axially removing the core from the molded fitting.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an elevation, partly in section, of a molding apparatus embodying the present invention;

FIG. 2 shows the central portion of the same apparatus after molding of a pipe fitting and with parts shown in different positions;

FIG. 3 is a section taken on line III shown in FIG. 1; and

FIG. 4 is a diagrammatic illustration of apparatus used to separate core parts to release the molded pipe fitting.

DETAILED DESCRIPTION OF THE INVENTION

A wide variety of thermoplastic materials can be used in the preparation of the tubular fittings prepared according to the present invention, including, for example, homopolymers such as polyethylene, polypropylene, and polybutene; copolymers of ethylene and vinyl esters of aliphatic carboxylic acids such as vinyl acetate and vinyl propionate; copolymers of ethylene and other alpha-olefins such as propylene, butene, hexene and octene; copolymers of ethylene and ethylenically unsaturated carboxylic acids such as acrylic acid, methacrylic acid and the like. Still other classes of thermoplastic materials which can be used include polyacetals, polyvinyl chloride and chlorinated polyvinyl chloride, polyamides and acrylics such as polymethyl methacrylate.

Preferred thermoplastic materials which can be used in the invention include polyethylene, ethylene-octene and ethylene-hexene copolymers.

The molding core used in the present invention may be in two parts, each part carrying one of said pivoted segments, the parts being axially separable.

Preferably each part of the core comprises an outer member on which the segment is pivoted and an inner axially slidable member. The axially slidable members may be interconnected by a bolt which draws the two parts of the core together, the bolt being rotatable so as to release the two parts.

The movement of the segments inwardly may be effected by axial movement of the inner core parts after they have been released.

For instance, each inner core part may have a shoulder adapted to engage a corresponding shoulder on one of the pivoted segments so as to cause it to pivot and withdraw the radial projection inwardly into the body of the core.

Stops may be provided to limit the axially outward movement of the inner core portions.

The outer periphery of the core may be provided with a shallow track or groove onto which the electrical wire may be wound. By arranging for the track to be very shallow in depth, for example, 0.1 mm, it has been found possible to withdraw the two core portions after moulding has been effected without the need to have a totally collapsible core or mandrel.

The method of producing a thermoplastic welding pipe fitting according to the present invention comprises:

winding a heater wire on the outer surface of a molding core, the molding core having one or more inwardly retractable segments carrying radially projecting posts;

placing a metallic electrically conductive terminal over each post to provide for attachment of the wire;

molding the fitting by placing the core in a molding machine and injecting plastic material so as to mold the fitting and terminal post surrounds in situ;

inwardly retracting each segment to remove the radially projecting posts from the terminals; and

axially removing the core from the molded fitting.

By use of the invention it is possible to mold the fitting as a single integral molding and in a one-stage molding process.

The invention will be more fully understood by reference to the Figures.

In FIG. 1 a core is shown in position in a molding machine ready for molding to commence. The core is divided into two parts 11 and 12 which meet at the junction 10.

Each of the two parts has an outer core member 13 and l3A and an inner axially retractable core member 14 and l4A. The inner core members 14 and 14A are held together by a bolt 15 threaded into a bore 16. The bolt may be rotated by a head member 17.

Pivoted at 18 and 19 in the outer core, members 13 and l3A are two segmental fingers 20 and 21 (see FIGS. 1, 2 and 3). Each segmental finger 20, 21 carries a radial projection 22, 23 respectively, adapted to facilitate winding a heater wire and/or to receive a terminal post 24, 25 during a molding operation.

Each segmental finger 20, 21 also has a small projection 26 and the two projections 26 are arranged to guide and support the wire during winding of the wire and to hold the wire in position during a subsequent molding operation.

The outer portions of the core also have a very shallow continuous spiral or other form of track or groove to receive wire 30 which is wound onto the core before molding commences.

Each inner core portion 14, l4A has a shoulder 27 and the shoulders are adapted, when the inner core members are retracted axially, to abut corresponding shoulders 28 on the collapsible segmental fingers 20 and 21.

In use, before being placed in a two-part mold 33, 33A (one half 33 only being shown in FIGS. 1 and 2) the core is assembled with the two halves of the core held together by the bolt 15 screwed into the bore 16. In this position it will be seen that the segmental fingers 20 and 21 form part of the outer surface of the core and the radial projections 22 and 23 and the small projections 26 extend radially beyond the surface of the core.

Wire is then wound on the outer surface of the core in the shallow trough or groove and the ends of the wire are wound round the post 22, are guided by the posts 26 and then wound around the post 23. Terminals 24 and 25 are attached to the ends of the wire and placed over the posts 22 and 23.

The core assembly is then placed in the mold half 33 and the metal terminals 24 and 25 are enclosed by shroud formers 22A, 23A as the mold is closed. Thermoplastic material such as polythene is then injection molded via passage 34 to form the fitting 29 with the wire 30 embedded in its inner surface and the terminals 24 and 25 molded into the fitting.

The mold may now be opened up and the molded fitting removed on the mold core.

It is now necessary to remove the core from the fitting. This is done by unscrewing the bolt 15 thus allowing the two parts of the core to separate. Before separating the two parts the head member 17 and the corresponding head member l7A are pulled axially and outwardly to the chain line position of FIG. 1 so that the shoulders 27 on the inner portions 14 and 14A of the core contact the shoulders 28 on the segmental fingers 20 and 21 causing the segmental portions to pivot. The finger 20 pivots clockwise and drops into the space within the core thus removing the radial projection 22 and projection 26 from the molded pipe fitting. Similarly the finger 21 pivots counterclockwise thus releasing the projections 23 and 26 from the core.

Stops 31 and 32 are provided to limit the axial movement of the inner core portions relative to the outer core portions and when the full extent of the axial movement of the inner core portions has taken place their outer ends will abut the heads of the stops and the core assembly will be removed axially from within the molded pipe fitting.

Axial movement of the two core parts may be effected by the apparatus shown in FIG. 4. The core parts are shown diagrammatically at 11 and 12 in the mould 33, 33A and are separated by attaching claws 35 and 36 carried on hydraulic rams 37 and 38 to head members 17 and l7A and simultaneously retracting the two parts of the core axially until the core parts are clear of the molded fitting.

Because the wire 30 is wound in a very shallow trough, it has been found possible to remove the core portions without the need to have a totally collapsible core or mandrel, the wire being retained in the molded fitting and simply sliding over the shallow trough.

The purpose of the projections 26 is to guide the wire and allow for change in pitch of the winding. Winding is in the same direction across both sides of the core.

Claims (8)

I claim:
1. An apparatus for molding heat weldable thermoplastic tubular fittings, the apparatus comprising a core in cooperation with an outer mold, the core having at least two segments, each said segment pivoted about a single point and collapsible inwardly of the core, each said segment bearing at least one first radial projection extending into a mold cavity formed between the core and the outer mold and a heater wire is wound and held in position around the first radial projections during subsequent molding.
2. An apparatus according to claim 1 further comprising a second radial projection on each said pivoted segment extending into the molding cavity, each said second projection receiving and supporting a terminal post during subsequent molding.
3. An apparatus according to claim 1 in which the core is in two parts, each part bearing one of said pivoted segments, the parts being axially separable.
4. An apparatus according to claim 3 in which each said part of the core comprises an outer member on which each said segment is pivoted about each said single point and an inner axially slidable member.
5. An apparatus according to claim 4 in which the axially slidable members are interconnected by a bolt which draws the two parts of the core together, the bolt being rotatable so as to release the two parts.
6. Apparatus according to claim 4 in which stops are provided to limit the axially outward movement of the inner axially slidable member.
7. Apparatus according to claim 1 in which the outer periphery of the core is provided with a shallow track or groove onto which the electrical wire is wound.
8. Apparatus according to claim 7 in which the track is of such shallow depth that the two core parts are withdrawn after molding and pivoting the two segments without a totally collapsible core.
US07/040,840 1986-04-23 1987-04-21 Apparatus for molding heat weldable pipe fittings Expired - Fee Related US4848718A (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
GB8609933 1986-04-23
GB08609933A GB2189737A (en) 1986-04-23 1986-04-23 Heat weldable pipe fittings

Publications (1)

Publication Number Publication Date
US4848718A true US4848718A (en) 1989-07-18

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Family Applications (1)

Application Number Title Priority Date Filing Date
US07/040,840 Expired - Fee Related US4848718A (en) 1986-04-23 1987-04-21 Apparatus for molding heat weldable pipe fittings

Country Status (9)

Country Link
US (1) US4848718A (en)
EP (1) EP0243062B1 (en)
JP (1) JPH0818353B2 (en)
AT (1) AT91458T (en)
CA (1) CA1271908A (en)
DE (2) DE3786480D1 (en)
ES (1) ES2043653T3 (en)
GB (1) GB2189737A (en)
HK (1) HK99394A (en)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5156864A (en) * 1991-02-06 1992-10-20 Guo Muh Juh Plastics threaded fitting molding mechanism
US5217731A (en) * 1990-10-30 1993-06-08 Rudolf Zahradnik Injection molding tool with retractable bead-forming segments
US5862585A (en) * 1994-03-31 1999-01-26 Glynwed Pipe Systems Limited Electrofusion couplers and method and apparatus for manufacturing

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB8618285D0 (en) * 1986-07-26 1986-09-03 Fusion Plastics Ltd Electroweldable sockets
GB9408461D0 (en) * 1994-04-28 1994-06-22 Glynwed Plastics Method of manufacturing and electrofusion coupler

Citations (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3061503A (en) * 1956-10-29 1962-10-30 Dow Chemical Co Method of joining pipes by means of an electrically heatable sleeve
US3062940A (en) * 1958-02-17 1962-11-06 Sud West Chemie G M B H Welding fitting
US3339242A (en) * 1963-11-12 1967-09-05 Ketch Plastics Ltd Collapsible tools for use in the moulding, casting or pressing of hollow articles
US3843088A (en) * 1972-02-01 1974-10-22 Tupperware Australia Pty Ltd Moulding apparatus
GB1440713A (en) * 1973-03-14 1976-06-23 Von Roll Ag Heat-weldable thermoplastic tubular fitting and a method of its manufacture
US3987276A (en) * 1974-05-10 1976-10-19 Georg Fischer Aktiengesellschaft Welded plastic attachment subassembly
US4000240A (en) * 1975-04-17 1976-12-28 Teletype Corporation Process of molding a reinforced flexible belt
US4075273A (en) * 1976-04-14 1978-02-21 Liautaud James P Method of making a coil form by injection molding
US4180542A (en) * 1973-09-04 1979-12-25 Celanese Corporation Methods for making molded plug and plug valve
US4362684A (en) * 1980-03-31 1982-12-07 George Fischer Aktiengesellschaft Process and apparatus for making a welding sleeve
US4365144A (en) * 1980-03-10 1982-12-21 Georg Fischer Aktiengesellschaft Apparatus for welding a joint between plastic pipes
US4420297A (en) * 1981-04-27 1983-12-13 Usm Corporation Retractable apparatus for shoe sole molds
US4476913A (en) * 1981-10-23 1984-10-16 Skf Kugellagerfabriken Gmbh Arrangement for pressure welding of a rolling bearing cage
SU1219393A1 (en) * 1984-04-21 1986-03-23 Вильнюсский Завод Пластмассовых Изделий Device for injection moulding of undirect plastic articles

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US1982279A (en) * 1928-04-05 1934-11-27 Herbert F Apple Apparatus for molding plastic material
US2781548A (en) * 1953-06-22 1957-02-19 Coats & Clark Cores and dies for producing hollow bodies
DE1048106B (en) * 1956-05-03 1958-12-31 Sued West Chemie Gmbh By welding to be connected Formstuecke, in particular fittings, made of thermoplastics
FR2174434A5 (en) * 1972-03-03 1973-10-12 Biotteau Gerard Shoes with moulded soles - anchored by direct moulding to uppers held against a former
JPS59366B2 (en) * 1975-08-19 1984-01-06 Kubota Ltd
DE3236933C2 (en) * 1982-10-06 1986-10-23 Kloeckner-Werke Ag, 4100 Duisburg, De
JPH0360647B2 (en) * 1983-02-03 1991-09-17 Toyoda Gosei Kk
AT387750B (en) * 1983-12-29 1989-03-10 Ifw Ind Formen Werkzeug Injection mold

Patent Citations (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3061503A (en) * 1956-10-29 1962-10-30 Dow Chemical Co Method of joining pipes by means of an electrically heatable sleeve
US3062940A (en) * 1958-02-17 1962-11-06 Sud West Chemie G M B H Welding fitting
US3339242A (en) * 1963-11-12 1967-09-05 Ketch Plastics Ltd Collapsible tools for use in the moulding, casting or pressing of hollow articles
US3843088A (en) * 1972-02-01 1974-10-22 Tupperware Australia Pty Ltd Moulding apparatus
GB1440713A (en) * 1973-03-14 1976-06-23 Von Roll Ag Heat-weldable thermoplastic tubular fitting and a method of its manufacture
US4180542A (en) * 1973-09-04 1979-12-25 Celanese Corporation Methods for making molded plug and plug valve
US3987276A (en) * 1974-05-10 1976-10-19 Georg Fischer Aktiengesellschaft Welded plastic attachment subassembly
US4000240A (en) * 1975-04-17 1976-12-28 Teletype Corporation Process of molding a reinforced flexible belt
US4075273A (en) * 1976-04-14 1978-02-21 Liautaud James P Method of making a coil form by injection molding
US4365144A (en) * 1980-03-10 1982-12-21 Georg Fischer Aktiengesellschaft Apparatus for welding a joint between plastic pipes
US4362684A (en) * 1980-03-31 1982-12-07 George Fischer Aktiengesellschaft Process and apparatus for making a welding sleeve
US4420297A (en) * 1981-04-27 1983-12-13 Usm Corporation Retractable apparatus for shoe sole molds
US4476913A (en) * 1981-10-23 1984-10-16 Skf Kugellagerfabriken Gmbh Arrangement for pressure welding of a rolling bearing cage
SU1219393A1 (en) * 1984-04-21 1986-03-23 Вильнюсский Завод Пластмассовых Изделий Device for injection moulding of undirect plastic articles

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5217731A (en) * 1990-10-30 1993-06-08 Rudolf Zahradnik Injection molding tool with retractable bead-forming segments
US5156864A (en) * 1991-02-06 1992-10-20 Guo Muh Juh Plastics threaded fitting molding mechanism
US5862585A (en) * 1994-03-31 1999-01-26 Glynwed Pipe Systems Limited Electrofusion couplers and method and apparatus for manufacturing

Also Published As

Publication number Publication date
EP0243062A3 (en) 1990-03-07
EP0243062A2 (en) 1987-10-28
JPH0818353B2 (en) 1996-02-28
AT91458T (en) 1993-07-15
JPS62267118A (en) 1987-11-19
GB2189737A (en) 1987-11-04
DE3786480D1 (en) 1993-08-19
EP0243062B1 (en) 1993-07-14
HK99394A (en) 1994-09-23
GB8609933D0 (en) 1986-05-29
CA1271908A (en) 1990-07-24
CA1271908A1 (en)
DE3786480T2 (en) 1994-01-05
ES2043653T3 (en) 1994-01-01

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Owner name: DU PONT (U.K.) LIMITED, WEDGWOOD WAY, GB-STEVENAGE

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Effective date: 19871202

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